Reproduction: semen composition: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Reproduction: semen composition

Sample item

A 29-year-old man with infertility has azoospermia, semen volume 0.8 mL, acidic pH and absent fructose. Testes are of normal size and FSH is normal. What is the most likely cause?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Congenital bilateral absence of the vas deferens with seminal vesicle hypoplasia

The seminal vesicles contribute most of the ejaculate volume, an alkaline fluid rich in fructose. When the vasa and seminal vesicles are absent, as in CFTR-related congenital bilateral absence of the vas deferens, the semen is low in volume, acidic and fructose-negative, with azoospermia. Spermatogenesis is normal, so testicular size and FSH are normal.

Option by option

  • A. Congenital bilateral absence of the vas deferens with seminal vesicle hypoplasia (correct)

    Loss of the seminal vesicle secretions and sperm conduit explains all the semen findings.

  • B. Retrograde ejaculation

    Retrograde ejaculation leaves sperm in post-ejaculation urine, with fructose present in normal secretions.

  • C. Sertoli cell-only syndrome

    Sertoli cell-only syndrome gives normal volume and fructose with small testes and high FSH.

  • D. Varicocele

    Varicocele causes oligospermia or poor quality sperm, with normal volume and fructose.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is A, Congenital bilateral absence of the vas deferens with seminal vesicle hypoplasia. The seminal vesicles contribute most of the ejaculate volume, an alkaline fluid rich in fructose.

Why is "Retrograde ejaculation" not the answer?

Retrograde ejaculation leaves sperm in post-ejaculation urine, with fructose present in normal secretions.

Why is "Sertoli cell-only syndrome" not the answer?

Sertoli cell-only syndrome gives normal volume and fructose with small testes and high FSH.

Why is "Varicocele" not the answer?

Varicocele causes oligospermia or poor quality sperm, with normal volume and fructose.

What concept does this question test?

It tests Reproduction: semen composition in Physiology. When the vasa and seminal vesicles are absent, as in CFTR-related congenital bilateral absence of the vas deferens, the semen is low in volume, acidic and fructose-negative, with azoospermia. Spermatogenesis is normal, so testicular size and FSH are normal.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Reproduction: semen composition?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.